Carbon Nitride C ₆ N ₇ ‐Supported Highly Dispersed Fe ₃ O ₄ for Efficient Photocatalytic Benzylamine Oxidative Coupling

Single‐atom catalysts, which feature atomically dispersed active sites that significantly enhance catalytic efficiency, still face persistent challenges in synthesis and stability. This study aims to develop efficient and stable highly dispersed materials as a promising alternative. Here, a new carbon nitride (UO) material with structure close to C 6 N 7 , where heptazine rings are connected via C–C bonds, was employed as a support. This material was further coupled with narrow‐bandgap magnetic Fe 3 O 4 to form an intimate contact interface, which promotes carrier separation and catalytic activity. Meanwhile, the extended conjugation in UO also facilitates broad spectral absorption and electron transport. In the visible‐light‐driven oxidation of benzylamine, the 4.8% Fe 3 O 4 /UO catalyst shows optimal performance, achieving a conversion rate of 97.6% within 6 h. This outstanding performance can be primarily attributed to the synergistic effects of high dispersion, efficient charge separation, and broad spectral response. Free radical trapping experiments and electron spin resonance spectroscopy confirmed that the primary active species are holes (h + ) and superoxide radicals (•O 2 − ). This work provides a feasible strategy for constructing low‐cost, easily synthesized, and stable highly dispersed catalysts, while also offering valuable insights for the design of efficient photocatalytic systems for benzylamine coupling reactions.